Table 3. Classification of the Association Between Influenza Vaccination and COVID-19 Outcomes Based on Receipt of PHE.

	2019-2020 Cohort
	Vaccinated	Unvaccinated
No. of individuals (%)	1 229 487 (53.9)	1 050 318 (46.1)
SARS-CoV-2 infection
No. of events (%)	2584 (0.21)	2745 (0.26)
HR (95% CI)	0.79 (0.75-0.83)	1 [Reference]
PHE 2018-2019, fully adjusted HR (95% CI)
Yes	0.62 (0.52-0.74)
No	0.81 (0.76-0.87)
SARS-CoV-2–associated hospitalization
No. of events (%)	992 (0.08)	980 (0.09)
HR (95% CI)	0.84 (0.77-0.92)	1 [Reference]
PHE 2018-2019, fully adjusted HR (95% CI)
Yes	0.64 (0.47-0.87)
No	0.86 (0.77-0.97)
SARS-CoV-2–associated death
No. of events (%)	428 (0.03)	441 (0.04)
HR (95% CI)	0.82 (0.72-0.93)	1 [Reference]
PHE 2018-2019, fully adjusted HR (95% CI)
Yes	0.46 (0.28-0.74)
No	0.78 (0.66-0.92)
SARS-CoV-2–associated hospitalization or death
No. of events (%)	1104 (0.09)	1093 (0.10)
HR (95% CI)	0.84 (0.77-0.91)	1 [Reference]
PHE 2018-2019, fully adjusted HR (95% CI)
Yes	0.66 (0.49-0.88)
No	0.85 (0.76-0.95)

Abbreviations: HR, hazard ratio; PHE, periodic health examination.